Absorption process and apparatus



Nov. 4, 1952 c. H. o. BERG BSORE'TION- PROCESS AND APPARATUS Filed Dec.27, 1948 Patented Nov. 4, 1952 UNITED STATES TENT OFFICE ABSORPTIONPROCESS AND APPARATUS Application December 2v, 194s, sei-iai No. 67,394

(o1. 19e-s) Y 20 Claims. l

I This invention relates to a method and apparatus for the separation ofgaseous mixtures and in particular relates to the treatment of gaseousmixtures which contain normally liquid components as vapors such as forexample a mixture of' hydrocarbon gases.

Such gaseousmixtures may 'be separated in a variety of conventional waysto recover the normally liquid components thereof such :as by coolingand partially condensing these components, by absorbing these componentsin a suitable solvent and separating the undissolved gas, condensing theentire gaseous mixture and distilling the condensate to obtain separatefractions thereof and other well known methods. In certain particularinstances, each of the aforementioned methods may be employed to certainadvantage over the others depending upon the` nature of the gaseousmixture to be separated,V the source of 'the gaseous mixturel thephysical condition of the mixture with regard to pressure andtemperature, and of course,v economic factors.

In the treatment of liquid hydrocarbons including catalytic and thermalcracking processes and the like, large quantities of gaseous mixturessynthetic organi-c compounds as well as other uses. The separation ofvsuch chemically vreactive compounds from gaseous mixtures may beeiiected` by the conventional processesrwhen a considerable loss of thereactive compounds may be tolerated. However, when it is desired toeffect a substantially complete and economic recovery of normally liquidhighly reactive compounds in their vapor state from other. gases,special precautions need to be exercised to effect the desired recovery.

' It is therefore a primary object of the present invention to provide amethod especially adapted to the highly efcient and economic recoveryfor the separation of normally liquid constitutents from admixture withother gases.

A further object of the present invention is to provide an improvedmethod whereby normally liquid constituents of high chemical activitymay be recovered from gaseous mixtures without damage or loss eiiicentlyand economically.

A more particular object of this invention is to provide a continuousprocess for the recovery of olefinic and unsaturated hydrocarbonconstituents which are normally liquid from gaseous mixtures containingthe same.

A specific object of this invention is to provide an improvedcombination process for the separation of valuable normally liquidhydrocarbon constituents of gaseous mixtures which involves apreliminary pretreatment of the gaseous mixture with a liquid phasecomprising condensed normally liquid hydrocarbons, and whichpretreatment `co-functions with a continuous selective adsorptionoperation in which the normally gaseous fraction is separated into aplurality of streams, one of which assists the pretreatment step.

Another object of this invention is to provide a particular type ofapparatus wherein the foregoing objects may be realized.

Other objects and advantages of the 4present invention will becomeapparent to those skilled in the art as the description an-dillustrations thereof proceed.

Briefly, the present invention comprises in its preferred embodiment theintroduction of a gaseous mixture containing yconstituents of widemolecular weight range including constituents which are normally liquidinto a pretreatment section or zone wherein the gaseous mixture iscontacted with a liquid phase comprising condensed normally liquidconstituents present in the gaseous mixture. The enriched liquid phasethus formed is subsequently warmed to a superatmospheric temperaturebelow the boiling point and, normally gaseous constituents are strippedout in the absence of absorption oils and high temperature surfa-ces.The peculiar mode of operation of the pretreatment section ashereinafter completely described permits the separation of the normallyliquid lconstituents present in the gaseous mixture from the normallygaseous constituents. Part of the normally liquid constituents thusrecovered are employed to contact further quantities of the gaseousmixture to be treated while the rest .are separated as a liquid product.The normally gaseous constituents are further treated with normallyliqui-d constituents to produce a dry gas from the pretreatment sectionwhich is substantially free of normally liquid constituents. The dry gasis then .contacted with a moving bed of solid granular adsorbent in aselective adsorption section whereby several substantially purefractions of the dry gas are produced. One of these fractions isreturned to the pretreatment step to aid in the refining of the normallyliquid constituents produced as a product from that step.

The process of the present invention may be applied with the realizationof the greatest advantage to a gaseous mixture containing normallyliquid constituents which are chemically active or thermally sensitivesuch as a gaseous mixture of hydrocarbons obtained from a hightemperature petroleum rening operation. Such a gas contains unsaturatedand olenic hydrocarbons which readily polymerize at temperatures aboveabout 250 F. and consequently may not be distilled from a condensedmixture thereof or may not be stripped from an adsorption oil solutionthereof without undue polymerization losses resulting. The presentprocess employs no absorption oil with attendant high temperaturestripping problems. No reboiling of the recovered hydrocarbon liquid isutilized in the process of the present invention. It has been found thatthere results considerable improvement in the efciency of separation ofthe type of gaseous mixtures given above and the complete freedom ofundue product losses, absorption oil purification problem since elevatedtemperatures normally employed in conventional processes are'notrequired in the present process, and of hydrates nearly alwaysencountered when hydrocarbon gases are treated at high pressure andrefrigeration temperatures in the presence of water vapor.

The following complete description of the process of this invention isconducted in conjunction with the accompanying drawing in which a owdiagram of the process is shown employing a pretreatment operation and aselective adsorption operation in the continuous separation of a gaseousmixture containing normally liquid constituents. For purposes ofillustration, the gaseous mixture will be considered to be a wet crackedgas produced in high temperature refining operations and containingconstituents of wide molecular weight range varying from hydrogen tohydrocarbon constituents having as high as ten carbon atoms permolecule. It should be understood, however, that the process is notlimited to the treatment of only cracked gases since it may be employedin the treatment of wet natural gas produced with crude petroleum andwhich contains natural gasoline as the normally liquid components. Theprocess is further not limited merely to the treatment of hydrocarbongases since it may be applied also to the recovery of chemically activesolvent vapors from gases and the like.

The description of the drawing will be conducted as a specific exampleof the operation of the process in which the gaseous mixture having thevcomposition given in Table l Will be separated into stabilized liquidpretreater bottoms product and a series of three gaseous products fromthe selective adsorption column.

The process of the present invention is applied to the above describedgaseous mixture to separate the C4 and higher molecular weighthydrocarbons, to be produced as the liquid product, from a dry gascontaining the C3 and lower molecular weight hydrocarbons and which issubsequently separated into three fractions of substantial purity in theselective adsorption operation. The overhead or lean gas product fromthe selective adsorption operation contains hydrogen and methane, theside cut gas product comprises a C2 hydrocarbon heart cut of the drygaswhile the bottoms fraction or rich gas product contains the C3hydrocarbons.

The feed gas mixture is introduced by means of line I0 at a ratecontrolled by valve II into pretreater column I2 at a rate of 1473 poundmols per hour. The pretreater column I2 is divided into three sectionsby means of upper divider I3 and lower divider I4. Lower divider isshown in the drawing with opening I'I, however, it may be substitutedwith a closed divider like upper divider I3 and the Ygas from zone I'Imay be conducted vialine Ida controlled by valve |511 to theV feedstream or directly into zone I'E. The column is therefore provided withprimary stripping zone I5, feed gas absorption zone I6 and liquidproduct stripping zone I'I. The construction of this particular columnis one in which bubble cap trays are employed, although other types oftrays or packing may be substituted.

The feed gas passes upwardly through absorption zone I6 incountercurrent contact to a downwardly flowing liquid stream ofhydrocarbons separated from the feed gas previously as a scrubbing agentor solvent and by means of which a substantial proportion of thenormally liquid hydrocarbons of the feed gas and the C4 hydrocarbons aredissolved. The temperature at which the contact in absorption zonel I6is effected is preferably less than about F., a typical operationaltemperature being an atmospheric temperature in the range of 80 F. to100 F. Additional coolers, not shown, may be incorporated in absorptionzone I8 to dissipate the heat of absorption. The enriched solventcollects in the bottom of absorption zone I6 above lower divider I4which is provided with riser I'I by means of Which the gases passdirectly from product stripping zone I'I upwardly into absorption zoneI6. The down owing rich solvent forms accumulation I8 on lower dividerIl! from which it is withdrawn via line I9 under the inuence of pump 20at a rate controlled by valve 2I which in turn is actuated by liquidlevel controller 22. This liquid comprises liquefied C4, Cs and C6 to400 F. hydrocarbons saturated with lower boiling hydrocarbons of thefeed gas mixture, mostly C2 and Ca hydrocarbons.

A portion of this liquid so withdrawn from lower divider I4 passes vialine 23 through exchanger 24 wherein it is warmed to a temperature ofabout F. in exchange with the bottoms product from liquid productstripper Il. The interchanged liquid subsequently passes via line 25through heater 26 in which the temperature is raised to between 200 F.and 250 F. depending upon the nature of the unsaturated hydrocarbonspresent in the liquid so that the temperature for polymerization andsimilar reactions is not exceeded. The preheated liquid then passes vialine 2'I on to the upper tra-y of product stripper Il, the liquid passesdownwardly therethrough eountereurrent to a rising stream of lean gasconsisting mainly of hydrogen and the lower' outlet oiprod-uct stripperI'I comprises the C4, C and Ce to 400: Fi hydrocarbons? saturated withhydrogen andA methane at a temperature of about 250 F. This product is`pumped by pump V via line 3Iy at' a rate controlledr by' valve 32 and isintroduced into exchanger 24 wherein the temperaturev of the liquidproduct is lowered to about 130 F.. Thel partially cooled liquidproductpasses via line 33 through. product cooler 34 wherein the temperature isdecreased to well below 100 F. suitable for storage. The

Vcooled liquid product then passes via line 35 at a rate of about 320pound mols per hour into liquid product storage tank 55 or it may beconducted via line 3'I controlled by valve 38 to further processingfacilities' not shown. The composition of theV liquid product thusobtained is given in, Table 2.

TABLE 2 Liquid product analysis Component:

Mol percent CgHs' 0.3 Cal-I3` 0.1 C4Hs 10.4 04H8 18.2 (24H10 0.6 Css12.8. Ceto- 400 F'. 57.6

The product thus obtained contains a relatively high percentage ofyhighly reactive unsaturated hydrocarbons including butadiene, variousbutyln enes, and unsaturated heavier hydrocarbons including pentenes,eyclopentadiene and the like. The success with which the pretreatmentoperation produces this liquid product without substantial loss of thevaluable unsaturated constituents may be attributed to the absence of ahigher molecular weight solvent other than the constituents present inthe feed gas mixture, the absence of a redistillation stage in which theliquid product must be reboiled and rectified, and

the general use of moderate temperatures in all parts of the apparatuspermitted by the heat interchange system and the above described liquidYproduct stripping procedure.

The remaining portion of the liquid withdrawn from accumulation I8 onlower divider I4 is pumped via line 39 through exchanger 4e in which thetemperature of the liquid is increased from. between about 80 F. and 100F. to about 178 F. The partially preheated liquid subse quently passesvia line 4I through heater e2 in which the liquid is hea-ted to atempera-ture between 200 F. and`250"v F. and below the polymerizationtemperature and is then passed via line 43 to the upper tray of primarystripper i5 to flow downwardly over the trays or packing. Theundissolved gases collecting in the upper portion of absorption sectionI5 comprise the C3 and lighter hydrocarbons saturated with constituentsof the liquid fraction at atmospheric 6i temperature. These gases are`removed via line 44 and" aI portion thereof passes via. line 45controlled. by valve 4S tio the selective adsorption section whilev theremainder passes. via line 4T controlled by valve 48 into interehanger449'. Herein the. temperature i'sincreased' to 200 F. and furtherheatedto the. temperature of liquid in primary stripper I5 byl passage throughline 5o and-heater?, I'. The preheated gases subsequentlyare introducedvia line 52.. into the lower portion of primary stripper I5 to contactthe down flowing liquid.` Within primary stripper I5 the upwardlyflowing gases remove the lower molecular weight normally gaseoushydrocarbons dissolved in the down flowing liquid producing anoverheadrecycle gasy comprising these desorbedlower molecular weighthydrocarbons saturated withv liquid hydrocarbon at the temperature ofthe primary stripper. Heat losses mayI bev counteracted byusing internalheaters, not shown'with in stripper I5. This gas is removed from the topof primary stripper I5 via line 53 and passed by" means of' blower 54 ata rate controlled by valve` to be combined with the feed gas introducedinto absorber IB after passing through inter-l changer 49 and recyclegas cooler 56. K

The liquid removed from the bottom of primary stripper I5 issubstantially free of lower boiling hydrocarbons and comprisesessentially the Cs and Cs to 400: F. hydrocarbons. This stream isremoved from an accumulation above upper d'1-- vider I3 by means of line5'! and is pumped. through interchanger 49 and cooler 58 by means ofpump 59. The cooled liquid then becomes the' y .solvent for the combinedfeed gas and' primary stripper recycle gas and passes via line 6I)controlled by valve 6I onto the uppermost tray 4of absorber I6. Itilowsl downwardly throughv absorber I6 as above described tc dissolvethe C4. and heavier molecular weight fraction from the gas and isultimately produced as theV liquid product.

The C3 and lower molecular weight hydrocarbons together with hydrogenseparated from the liquid product in the pretreater section are removedfrom the upper portion of absorber I6 by feed gas.

means of line 45 controlled by valve 46 as the pretreater dry gas and isintroduced by means of line 45 into selective adsorption column 80 as aThis gas also contains the gasesfremoved from the top of productstripper IT. If' desired, a portion of thisy dry gas may be producedwithout furthertreatment via line. 8I controlled by valve Si. from thesystem. This gas.

has the following composition:

TABLE v3 Pretreater dry ccs' or selective adsorber feedv gas Component:Mol percent H2v 155.1 CIEL;e 37.8 C2H2 0.1 C21-I4 23.2 C21-Is 7.7 (33H613.2k CaHs 1.2 (14H6 0.3 C4Ha 0.5 04H10 0.0 Css 0.5 (3s-400 F. 04

This gas is introducedinto selective adsorption column 80 at atemperature of about 80 F. to 100 F. at a rate of 1410 pound mols perhour when the entire pretreatment section dry gas is to be separated.

The selective adsorptive column is provided with hopper 83, cooling zone04, overhead gas or lean gas disengaging zone 95, adsorption zone 86,feed gas engaging zone 81, primary rectification Vzone 88, side cutdisengaging zone 89, secondary rectication zone 90, rich gas or bottomsproduct disengaging zone 9|, steaming zone 92, stripping gas engagingzone 93, heating zone 94, adsorbent feeder zone 95 and sealing leg 96.The solid granular adsorbent, which in the preferred modification isactivated vegetable charcoal, is passed downwardly by gravityr throughthe aforementioned zones in the form of a dense compact moving bed andpasses from the bottom of the column via sealing leg 9G throughadsorbent :dow control H valve 91 and transfer line 98 into inductionzone 99. A lift gas is introduced via line |09 into induction zone 99 toform an adsorbent-lift gas suspension therein. The rate at which thesuspension is'formed is controlled by varying the quantity of lift gaspassing from lift gas inlet zone via line |02 controlled by valve |83which in turn is actuated by level controller |04 and introduced intosolids inlet zone |05 in the upper portion of the induction zone.pension thus formed passes upwardly through lift line |96 intoimpactless separator |01 wherein the suspension is broken. The separatedlift gas containing elutriated adsorbent fines suspended therein and theseparated adsorbent pass as substantially independent phases by throughtransfer line |08 into adsorbent hopper 83. The lift gas and nes passvia line |09 into centrifugal separator 0 in which the suspended finesare separated. The fines-free lift gas subsequently passes via line intosuction inlet of gas blower ||2 which reintroduces the lift gas via line|00 at a rate controlled by valve ||3 into induction zone 99. Thus acontinuously recirculated stream of adsorbent is maintained as a movingbed through the column. In the preferred modification, the adsorbentemployed is activated coconut charcoal in which case the adsorbentcirculation rateis about 175,000 pounds per hour.

The feed gas mixture is introduced as above described into feed gasengaging zone 81 wherefrom it passes upwardly through adsorption zone 86in countercurrent contact to a downward flow of adsorbent.' Theadsorbent to feed gas ratio is such that the C3 and C2 hydrocarbons arepreferentially adsorbed together with a small proportion of lighterconstituents to form a rich adsorbent while the methane and hydrogentogether with a small amount ofy C2 hydrocarbons remain substantiallyunadsorbed. The unadsorbed gases pass to the top of adsorption zone 86from which a portion is removed as an overhead or lean gas product vialine H0 controlled by valve ||5 and sent to production 0r furtherprocessing facilities not shown. Another portion of this lean gasproduct may be removed from zone 85 via line controlled by valve I l1together with a portion of lift gas if desired passing through line ||8controlled by valve ||9 may be recirculated through lines and 28 to beintroduced into the bottom of product stripper |1 in shown. A portion ofthe substantially unad- The lift gas sussorbed gases passes upwardlythrough the vtubes of cooling zone 84 in countercurrent contact with theadsorbent therein to presaturate the adsorbent with lean gas productconstituents and to desorb traces of adsorbed stripping gas therebydirectly cooling the adsorbent. This gas stream is called the purge gasand contains about 55% to 60% hydrogen and 40% to 45% methane,approximately the composition of the lift gas, and may be used as thestripping gas in product stripper |1. It combines with the recirculatinglift gas stream in the top of column 80.

The lean gas or adsorber overhead product is removed from the system ata rate of 490 pound mols per hour and has the composition given in Table4.

TABLE 4 Lean gas analysis Component: Mol percent H2 28.5y CH4 '71.0lC21-I4 0.5-

Total 100.0

The rich adsorbent subsequently passes from adsorption zone 89 intoprimary rectication zone 88 wherein it is contacted with acountercurrent flow of a side cut gas reflux containing C2 and C:hydrocarbon gases. Small amounts of absorbed hydrogen and methane arepreferentially desorbed from the rich adsorbent to join the lean gasproduct leaving a rectified adsorbent principally containing adsorbed C2and C3 hydrocarbons. The rectified adsorbent then passes into secondaryrectification zone wherein it is contacted with a countercurrent flow ofrich gas reflux containing C3 hydrocarbons thereby preferentiallydesorbing the Cz hydrocarbons which collect in side cut gas disengagingzone 89. A portion of this gas is employed as reflux in primaryrectification zone 88 and the remainder is removed as a side cut gasproduct via line |25 ata rate' of 437 pound mols per hour controlled byvalve |26. Temperature recorder controller |21 operates in conjunctionwith thermocouple point |28 positioned in direct contact with theadsorbent in primary rectification zone 88 to vary valve |26. thecomposition given in Table 5.

TABLE 5 .Sfide cut product gas analysis Component: Mol per cent CHl 0.1

C2H6 24.2 Cs 0 6 The rectified adsorbent passes into preferentialdesorption zone 92 wherein it is contacted with a countercurrent iiow ofstripping gas introduced via line |29 controlled by valve |30 intostripping gas engaging Zone 93. The adsorbed C3 hydrocarbons arepreferentially desorbed as a rich gas, a portion of which is employed asthe C3 reflux gas in secondary rectification zone 9|) and the remainingportion of which is passed via line |3| at a rate ofV 203 pound mols perhour controlled by Valve |32 which in turn is actuated by temperaturerecorder controller |33 operating in conjunction with thermocouple point|34 contacting the adsorbent in secondary rectification zone 90. Thedesorbed C3 hydrocarbons, together The side cut gas product hasv rwith.some ,stripping gas, are introduced into rich gas cooler and the.cooled Vmix-ture resulting is passed via line 36 into separator |31.The preferred stripping gas comprises steam and the condensed waterl isremoved from the lowerl poi-f tion `of separator |37 .via line |33controlled by valve |39 .and liquid level controller |45. A rich gasproduct is removed by means of line A|41 controlled by valve |592 andhas the composition .given in Table ;6. TABLE 6 sich aus productanalysis Component: Mol per cent ;C2Hs -f- -".0 .1 Cal-I6 ,91;.0 CfsHs8.5 Galia-i- 101.5

the partially Stripped adsorbent :passes than through the tubos ofheating zone 'S4 wherein' the adsorbent is indirectly heated andcontacted countercurrently with further quantities of stripping gaswhereby remaining portions of adsorbed rich gas constituents aredesorbed. In one vInodioaticn this heated lac lsorbent is concurrentlycontacted with estrena of Stripping ses which removed -below iheatingjzone 55 line |5115, controlled valve M6 and it may 'be combined ifVdesired with the 4rich :gas product or combined and recirculatedwithstripping lgas introduced into Stripping sesngagflg 1.29.11@ 9.3 L'

The adsorbentremoved from "heating zone 9!! is at a temperatureof aboutllfio F, and Ais saturated with adsorbed stripping gas. VThe adsnrbentpasses at a` vcontrolled -flow rate through adsorbent feeder Zone 95 andsubsequently downward through scaling leg :9 6 through adsorbent flowcontrol valve 91 which is employed to maintain lsealing -leg 95 -ful-l of dense phase adsorbent.

A portion of the recirculated stripping gas passes downward-ly .throughsealing leg 95 and` a portion of the lift gas passes upwardly throughtransfer line 98 since this transfer line is not generally maintainedfull of adsorbent but ythe adsorbent flows along the lower surface yintoinduction zone 19e. Toprevent the lift gas `from entering A:the lowerApart Vof the Aadsorption .column and .to prevent undueaccumulations ofstripping gas from entering the lift gas .recirculation system, .-asealgas comprising stripping and liftgas is -zremoved from the chamber.of char-coal'iiow f carbon constituents.

control valve Q1 via line |47 at a .rate controlled by lyalye |43. 'This`gas is .discarded .or ,sentto fuel, .or combined .with the lean gasproduct if desired. The adsorbent is recireulated then .as abovedescribed to the upper portion of ,selective adsorption column `til topass through cooler' 84 wherein 'it is ,cooled .to 10.0'.F. rprior tocontacting further .ouantities fofithe gaseous mixture.

yQperationof `the `v:process .ofthe present Vinventionrin connectionwith :typical wetcracked gases, as described 1in the :foregoing exampleYand illus.- tratedain the drawing, hasfbeen found .,todecrease markedlytheutilitiesrequirement for the separa.- tion and achieve yanoutstanding reduction in the quantity-of unsaturated and chemicallyTreactive :normally -liquidiconstituents -lost fwhen such gaseousAmixtures Aare treated Ein 4conv entional absorption loil `ordistillation processes. In the apparatus -of Athe present Ainvention#there a complete absence of heat'transfersurfaces which ordinarily ofnecessity Amust 1bemaintained nat temperatures well above Vthetemperatures `-`to which the-stream in the conventional absorption anddistillation processes must be heated. It has been found that thepresence lof these surfaces rapidly degrade absorption oil when used dueto the rapid polymerization .of unsaturated hydro- The usual fouling ,ofheat transfer surfaces by these polymerizable constituents usuallyencountered in distillation processes where the liquid product isdistilled and Vproduced as `an .overhead product is eliminated. The useof a light gas which, under conditions of contact is only slightlyabsorbable in the liquid product as a stripping gas, markedly assists inthe production `of high quality unsaturated liquid vproducts at asubstantially increased yield over that usually found in conventionaltreatments. The selective adsorption process and the herein describedimproved pretreatment process cooperatewith one another in the mannerdescribed above to permitthe eii'icient and easily controlled separationof typically wet cracked gases into desirable constituents in conditionfor syn-l thetic chemicals manufacture or for conversion into internalcombustion engine fuels of high quality. Adsorbents other than activatedcharcoal may be employed if desired including silica gel, aluxninumoxide, iron oxide, and other well vknown solid granular adsorbents,Preferably, the mesh size of granularadsorbent iskfrom 10 -to 30 mesh,although particles as large as 2 mesh to `as small als i199 mesh .may be.employed rAs above stated the principles o f the present process areobviously applicable to gaseous mixtures containingcondensablevconstituents other than those employed to facilitatedescription thereof and that the scope of the present invention is to:be limited only by the following claims.

A p rocess for the separation of thermally sensitive `normally liquidhydrocarbon constituente .from a saseOuS mixture .thereof which Comfprises countercurrently contacting said gaseous mixture all absorptionzone with a condensed stream of s aid normally liquid constituentsrecovered :from said gaseous mixture forming an enriched condensate andleaving normally gas-,- ecus constituents in the gas phase, heating oneportion of said enriched condensate to a superatrnospheric temperatureless than 250 F., heating one portion of s aid normally gaseous constituents `toapprOXimately the same temperature. countercurrently contactinga portion of the heated gas and a portion of the heated liquid in aprimary Astripping zone forming .a stripped condensate free of normallygaseous constituents and :a stripped gas rsaturated with normallyVliquid constituents, cooling said strippedgas, combining Asaid strippedgas with said gaseous mixture-to be separated, cooling said strippedcondensate to atmospheric temperature, contacting the cool strippedcondensate with vfurther quantities of said gaseousmixture, contactingthe remaining portion of the normally gaseous constituents profduced insaid 7absorption zone with a inni/,ing bed of solidgranularadsorbentthereby ,adsorbing the higher molecular' Weight constituents .thereofleaving the :lower molecular weight constituents Substantially.unadsorboi employing a .portonlof the substantially lnadsorbed gasesthus obtained to contact therexnaining portionfof said enrichedcondensate :in .a :liquid .product .stripping zone thereby stripping,T19rnially `gaseous ,constituents therefrom, `passing the stripping easand normally gaseous constituents stripped from said liquid product intosaid absorption Zone and re-V moving the thermally sensitive vnormallyliquid hydrocarbon constituents substantially free of normally gaseoushydrocarbon constituents from said liquid product stripping zone.

2. A process according to claim 1 wherein said granular adsorbentcomprises activated charcoal.

3. A process for the separation of higher molecular weight hydrocarbonsfrom admixture with lower molecular weight hydrocarbons in gaseousmixtures thereof which comprises contacting said gaseous mixture with astream of condensed higher molecular weight hydrocarbons in anabsorption zone forming an enriched hydrocarbon liquid fraction and adepleted gaseous hydrocarbon fraction, heating a first portion of saidenriched liquid fraction, heating one portion of said depleted gaseousfraction to substantially the same temperature as the rst portion ofsaid enriched liquid fraction, contacting the two heated streamscountercurrently in a primary stripping zone to form a liquid fractionsubstantially free of said lower molecular weight hydrocarbons and agaseous fraction saturated with said higher molecular weighthydrocarbons, L

cooling said gaseous fraction saturated with normally liquidhydrocarbons, combining said gaseous fraction with said gaseous mixtureto be separated, cooling said last-named liquid fraction produced insaid primary stripping zone,

contacting the thus cooled liquid fraction with further quantities ofsaid gaseous mixture in said absorption zone, removing the remainingportion of said depleted gaseous fraction from said absorption zone,introducing the remaining portion of said enriched liquid fractionproduced in said absorption zone into a liquid product stripping zone,countercurrently contacting said remaining portion with a portion ofsaid depleted gaseous fraction thereby stripping low molecular weighthydrocarbons from said liquid and producing the stripped hydrocarbonliquid as a liquid product from said liquid productr stripping zonesubstantially free from absorbed `low molecularweight normally gaseoushydrocarbons.

4i. `A process according to claim 3 wherein said hydrocarbon gas mixtureto be separated comprises a wet cracked hydrocarbongas containinghydrogen and hydrocarbon constituents of wide molecular weight range,said liquid product comprises the C4 andV higher molecular weighthydrocarbons separated therefrom, the C3 and lower molecular weighthydrocarbons and hydrogen being separated from said enriched hydrocarbonliquid obtained in saidY absorption Zone by contacting said enrichedhydrocarbon liquid in said liquid product stripping Zone at asuperatmospheric temperature below about 250 with a low molecular weightstripping gas in theabsence of indirect heating to produce said liquidproduct. A

5. A process according to claim 3 wherein said rst portion of. enrichedhydrocarbon liquid is heated by indirect heat exchange with the strippedhydrocarbon liquid removed from said primary stripping Zone, saiddepleted gaseous hydrocarbonfraction is heated by indirect heat exchangewith the gaseous hydrocarbon fraction saturated with normally liquidhydrocarbons removed from said primary stripping zone and said strippedhydrocarbon liquid product is cooled by indirect heat exchange with saidsecond fraction of enriched hydrocarbon liquid removed from saidabsorption zone.

A 6. A process according to claim 3 wherein said portion ,of saiddepleted gaseous hydrocarbon fraction employed to strip said liquidhydrocarbon product in said product stripping Zone is obtained by thesteps of contacting a part of said depleted gaseous hydrocarbon fractionremoved from said absorption zone with a moving bed of solid granularadsorbent whereby the higher molecular weight hydrocarbon gases of saiddepleted gaseous fraction are adsorbed leaving the lower molecularweight hydrocarbon gases substantially unadsorbed and introducing aportion of said substantially unadsorbed gas into said liquidhydrocarbon product stripping zone.

7. A process for the separation of normally liquid hydrocarbonconstituents from a gaseous mixture thereof with normally gaseoushydrocarbon constituents which comprises countercurrently contactingsaid gaseous mixture in an absorption Zone with a condensed stream ofsaid normally liquid constituents recovered from said gaseous mixtureforming an enriched condensate and leaving normally gaseous constituentsin the gas phase, heating one portion of said enriched condensate,heating one portion of said normally gaseous constituents toapproximately the same temperature, countercurrently contacting theheated gas with a portion of the heated liquid in a primary strippingzone forming a stripped condensate free of normally gaseous constituentsand a stripped gas saturated with normally liquid constituents, coolingsaid stripped gas, combining said stripped gas with said gaseous mixtureto be separated, cooling said stripped condensate, contacting the coolstripped condensate with further quantities of said gaseous mixture,contacting the remaining portion of the normally gaseous constituentsproduced in said absorption zone with a moving bed of solid granularadsorbent thereby adsorbing the higher molecular weight constituentsthereof leaving the lower molecular weight constituents substantiallyunadsorbed, employing a portion of the substantially unadsorbed gasesthus obtained to contact the remaining portion of said enrichedcondensate in a liquid product stripping zone thereby stripping normallygaseous constituents therefrom, passing the stripping gas and normallygaseous constituents stripped from said liquid'product into saidabsorption zone and removing the normally liquid hydrocarbonconstituents substantially free of normally gaseous hydrocarbonconstituents from said liquid product stripping zone.

8. A process for the separation of normally liquid hydrocarbonconstituents from a gaseous mixture thereof with normally gaseoushydrocarbon constituents which comprises countercurrently contactingsaid gaseous mixture in an absorption zone with a condensed stream ofsaid normally liquid constituents recovered from said gaseous mixtureforming an enriched condensate and leaving normally gaseous constituentsin the gas phase, heating one portion of said enriched condensate,heating oneportion of said normally gaseous constituents toapproximately the same temperature, countercurrently contacting theheated gas with a portion of the heated liquid in a primary strippingzone forming a stripped condensate free of normally gaseous constituentsand a stripped gas saturated with normally liquidconstituents, cooling`said stripped gas, combining said stripped gas with said gaseousmixture tojbe separated, cooling (said stripped condensate, contactingthe coolstripped` condensate stripper section, a conduit for gasconnecting the top of said primary stripper section to said inletconduit for said gaseous mixture, a conduit for liquid connecting thebottom of said absorption section to the top of said primary strippersection, a conduit for liquid connecting the bottom of said primarystripper section with the top of said absorption section, a conduit forliquid connecting the bottom of said absorption section with the top ofsaid product stripper section, an outlet conduit for liquid product fromthe bottom of said product stripper section, an outlet conduit for gasfrom the top of said absorption section, and an inlet conduit for gasinto the bottom of said liquid product stripper section.

15. An apparatus for separating normally liquid constituents from agaseous mixture thereof which comprises a vertical contacting column, apair of spaced lateral divider plates Within said column forming anupper primary stripper section, an intermediate absorption section, anda lower liquid product stripper section, spaced bubble trays Within eachof said sections, an inlet conduit for said gaseous mixture into thebottom of said absorption section, a conduit for unabsorbed gasconnecting the top of said absorption section With the bottom of saidprimary stripper section, indirect heating means associated with saidlast-named conduit, a conduit for gas connecting the top of said primarystripper section to said inlet conduit for said gaseous mixture,indirect cooling means in said lastnamed conduit, a conduit for liquidconnecting the bottom of said absorption section to the top of saidprimary stripper section, indirect heating` means in said last-namedconduit, a conduit for liquid connecting the bottom of said primarystripper section with the top of said absorption section, indirectcooling means in said lastnamed conduit, a conduit for liquid connecting.the bottom of said absorption section with the top of said productstripper section, indirect heating means in said last-named conduit, anoutlet conduit for liquid product from the bottom ofv said productstripper section, indirect cooling means in said outlet conduit forliquid product, an outlet conduit for gas from the top of absorptionsection, and an inlet conduit for gas Iinto the bottom of said productstripper section.

16. An apparatus for separating normally liquid constituents from agaseous mixture thereof which comprises a vertical contacting column, apairI of spaced lateral divider plates within said column forming anupper primary stripper section, an intermediate absorption section, anda lowerliquid product stripper section, spaced bubble trays within eachof said sections, a vertical selective adsorption column provided atsuccessively lower levels therein with a tubular cooling section, anadsorption section, a rectication section and a tubular desorptionsection, conduit means for conveying adsorbent removed from saiddesorption section to said tubular cooling section, an inlet conduit forsaid gaseous mixture into the bottom of said intermediate absorptionsection, a conduit for unabsorbed gas connecting the top of saidabsorption section through an indirect heating means with the bottom ofsaid primary stripper section, a conduit for gas connecting the top ofsaid primary stripper section through an indirect cooling means to saidinlet conduit for said gaseous mixture, a conduit for liquid connectingthe bottom of said vabsorption section through an'indirect heating meansto the top of said primary stripper section, a conduit for liquidconnecting the bottom of said primary stripper section through anindirect cooling means with the top of said absorption section, aconduit for liquid connecting the bottom of said absorption sectionthrough an indirect heating means with the top of said product strippersection, an outlet conduit for liquid product from the bottom of saidproduct stripper section through an indirect cooling means, a conduitfor gas connecting the top of said absorption section with the bottom ofsaid absorption section in said selective adsorption column, an outletconduit for unadsorbed gas from the top of said adsorption sectioncommunicating with the bottom of said liquid product .stripper section,and an outlet conduit from said desorption section for desorbed gases.

1'7. An apparatus for separating normally liquid constituents from agaseous mixture thereof which comprises a primary stripper chamber, anabsorption chamber and a liquid product stripper chamber, spaced bubbletrays within each of said chambers, an inlet conduit for said gaseousmixture into the bottom of said absorption chamber, a conduit forunabsorbed gas connecting the top of said absorption chamber with thebottom of said primary stripper chamber, a conduit for gas connectingthe top of said primary stripper chamber to said inlet conduit for saidgaseous mixture into said absorption chamber, a conduit for liquidconnecting the bottom of said absorption chamber to the top of saidprimary stripper chamber, a conduit for liquid connecting the bottom ofsaid primary stripper chamber to the top of said absorption chamber, aconduit for liquid connecting the bottom of said absorption chamber withthe top of said product stripper chamber, a conduit for gas connectingthe top of said product stripper chamber with the bottom of saidabsorption chamber, an outlet conduit for liquid product from the bottomof said product stripper chamber. an outlet conduit for gas from lthetop of said absorption chamber and an inlet conduit for stripping gasinto the bottom of said liquid product stripper chamber.

18. An, apparatus for separating normally liquid constituents from agaseous mixture thereof which comprises a primary stripper chamber, anabsorption chamber, and a liquid product stripper chamber, spaced bubbletrays within each of said chambers, a vertical selective adsorptioncolumn provided at successively lower levels therein with a tubularcooling section, an adsorption section, a, rectification section and atubular desorption section, conduit means for conveying adsorbentremoved from-said desorption section to said tubular cooling section, aninlet conduit for said gaseous mixture into the bottom of saidadsorption chamber, a conduit for unabsorbed gas connecting the top ofsaid absorption chamber with the bottom of said primary stripperchamber, a conduit for gas connecting the top of said primary stripperchamber to said inlet conduit for said gaseous mixture, a conduit forliquid connecting the bottom of said absorption chamber to the top ofsaid primary stripper chamber, a conduit for liquid connecting thebottom of said primary stripper chamber with the top of said absorptionchamber, a conduit for liquid connecting the bottom of said absorptionchamber with the top of said product stripper chamber, a conduit for gasconnecting the top of said product stripper section with the bottom ofsaid absorption section, an outlet conduit for liquid product from thebottom of said product stripper chamber, a conduit for gas connectingthe top of said absorption chamber with the bottom of said adsorptionsection in said selective adsorption column, an outlet conduit forunadsorbed gas from the top of said adsorption section connecting saidadsorption section with the bottom of said liquid product stripperchamber, and an outlet conduit from said desorption section for desorbedgases.

19. An apparatus for separating normally liquid constituents from agaseous mixture thereof which comprises a primary stripper chamber, anabsorption chamber and a liquid product stripper chamber, spaced bubbletrays within each of said chambers, a vertical selective adsorptioncolumn provided at successively lower levels therein with a tubularcooling section, an adsorption section, a rectication section and atubular desorption section, conduit means for conveying adsorbentremoved from said desorption section to said tubular cooling section, aninlet conduit for said gaseous mixture into the bottom of saidabsorption chamber, a conduit for unabsorbed gas connecting the top ofsaid absorption chamber through indirect heating means with the bottomof said primary stripper chamber, a conduit for gas connecting the topof said primary stripper chamber through indirect cooling means withsaid inlet conduit for said gaseous mixture, a conduit for liquidcommunicating the bottom of said absorption chamber through indirectheating means with the top of said primary stripper chamber, a conduitfor liquid connecting the bottom of said primary stripper chamberthrough indirect cooling means with the top of said absorption chamber,a conduit for liquid connecting the bottom of said absorption chamberthrough indirect heating means with the top of said product stripperchamber, a conduit for gas connecting the top of said product strippersection with the bottom of said absorption section, an outlet conduitfor liquid product from the bottom of said product stripper chamberprovided with indirect cooling means, a conduit for gas connecting thetop of said absorption chamber with the Y bottom of said adsorptionsection in said selec- 18 uid constituents from a gaseous mixturethereof which comprises a primary stripper chamber, an absorptionchamber and a liquid product stripper chamber, spaced bubble trayswithin each of said chambers, an inlet conduit for said gaseous mixtureinto the bottom of said absorption chamber, a conduit for unabsorbed gasconnecting the top of said absorption chamber through indirect heatingmeans With the bottom of said primary stripper chamber, a conduit forgas connecting the top of said primary stripper chamber through indirectcooling means with said inlet conduit for said gaseous mixture, aconduit for liquid communicating the bottom of said absorption chamberthrough indirect heating means with the top of said primary stripperchamber, a conduit for liquid connecting the bottom of said primarystripper chamber through indirect cooling means with the top of saidabsorption chamber, a conduit for liquid connecting the bottom of saidabsorption chamber through indirect heating means with the top of saidproduct stripper chamber, a conduit for gas connecting'the top of saidproduct stripper section with the bottom of said absorption section, anoutlet conduit for liquid product from the bottom of said productstripper chamber provided with indirect cooling means, a conduit for gasfrom the top of said absorption chamber, and a conduit for gas into thebottom of said liquid product stripper chamber.

CLYDE H. O. BERG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,422,007 Soddy July 4, 19222,038,314 Ragatz Apr. 21, 1936 2,074,644 Drennan Mar. 23, 1937 2,117,548Drennan May 17, 1938 2,134,836 Ostergaard Nov. 1, 1938 2,262,202 Ragatzet al Nov. 11, 1941 2,290,957 I-Iachmuth July 28, 1942 2,293,241Campbell Aug. 18, 1942 2,345,934 Gregory Apr. 4, 1944 2,367,284 KaplanJan. 16, 1945 2,468,750 Gudenrath May 3, 1949 OTHER REFERENCES Berg etal.: The Petroleum Engineer of May. 1947, pages 115, 116 and 118.

1. A PROCESS FOR THE SEPARATION OF THERMALLY SENSITIVE NORMALLY LIQUIDHYDROCARBON CONSISTUENTS FROM A GASEOUS MIXTURE THEREOF WHICH COMPRISESCOUNTERCURRENTLY CONTACTING SAID GASEOUS MIXTURE IN AN ABSORPTION ZONEWITH A CONDENSED STREAM OF SAID NORMALLY LIQUID CONSTITUENTS RECOVEREDFROM SAID GASEOUS MIXTURE FORMING AN ENRICHED CONDENSATE AND LEAVINGNORMALLY GASEOUS CONSTITUENTS IN THE GAS PHASE, HEATING ONE PORTION OFSAID ENRICHED CONDENSATE TO A SUPERATMOSPHERIC TEMPERATURE LESS THAN250* F., HEATING ONE PORTION OF SAID NORMALLY GASEOUS CONSTITUENTS TOAPPROXIMATELY THE SAME TEMPERATURE, COUNTERCURRENTLY CONTACTING APORTIONOF THE HEATED GAS AND A PORTION OF THE HEATED LIQUID IN A PRIMARYSTRIPPING ZONE FORMING A STRIPPED CONDENSATE FREE OF NORMALLY GASEOUSCONSTITUENTS AND A STRIPPED GAS SATURATED WITH NORMALLY LIQUIDCONSTITUENTS, COOLING SAID STRIPPED GAS, COMBINING SAID STRIPPED GASWITH SAID GASEOUS MIXTURE TO BE SEPARATED, COOLING SAID STRIPPEDCONDENSATE TO ATMOSPHERIC TEMPERATURE, CONTACTING THE COOL STRIPPEDCONDENSATE WITH FURTHER QUANTITIES OF